1. Field of the Invention
The present invention relates to a resin composition and a coating method using the same.
2. Related Art
When compositions such as those of photosensitive resins are coated on surfaces of semiconductor wafers or glass substrates, rotational coating processes, screen printing coating processes, dipping coating processes, spray coating processes, etc. are typically employed. In all of these processes, the surfaces of semiconductor wafers or glass substrates are coated by a liquid-form coating liquid; therefore, when substrates to be coated have concave portions such as holes (pores) or trenches between wiring, the coating liquid enters into the concave portions, and thus the coating liquid, which has entered into the concave portions, is required to be removed at a subsequent step. When the concave portion is a hole in particular, there is a problem in that photosensitive resin residue remains within the holes since developer is unlikely to enter the hole during the developing step which is conducted after the photosensitive resin has entered the holes. The residue may be removed by increasing development time; however, this approach suffers from a problem in that the entire thickness of the resulting resin layer decreases, i.e. so-called “film reduction” occurs. In order to solve this problem, attempts have been made to form a thin film layer of photosensitive resin composition in which the photosensitive resin composition does not enter into the holes in particular.
A process, referred to as a tenting process, is used to form a thin film layer of photosensitive resin composition on substrates with concave portions. In such a process, tenting refers to the ability of the photosensitive resin composition to cover a substrate and concave portions of the substrate without entering into voids defined by the concave portions. In the tenting process, a photosensitive resin composition is coated and dried onto a release film such as polyester film to form a so-called dry film, and the dry film is laminated onto the surface of substrates by thermal compression etc., then the release film is peeled off. Consequently, a thin film layer of photosensitive resin composition can be easily formed over concave portions (Patent Document 1).
[Patent Document 1] Japanese Unexamined Patent Application, First Publication No. Hei 10-172431